Shocking service from We Fix Fourways Crossing

I am so disappointed at the lack of service from We Fix Fourways Crossing. I had a battery replaced in an iphone in december last year. The battery would not charge and I took phone back several times and each time the lady that served me said there was nothing wrong with it. I recently took phone back to replace screen and they quoted me for screen and faulty battery. I told them about the replacement battery in December and they said the battery has 6 month warranty so I have to buy a new one. After much convincing me that I had NOT been in about the battery within the 6 months they said they would speak to the regional manager. Till now (and I have followed up several times) they have NEVER phoned me back as promised. The lack of service is shocking !!!!!!!! All I want is for them to replace a faulty battery that was sold to me - the cost is R350 but it is the principle of the matter - they sold me a faulty battery, I took it back within the 6 months and they have never phoned back. What about customer service????